Design Engineers Take On Component Police

Design engineers want to use parts that work. Component engineers and purchasing agents want as few parts as possible. Put the two together, and trouble ensues.

There have been times and places where a designer could make the call on the particular component needed without too much opposition from the Component Engineering group -- usually because there was no such group. But, any corporation that includes a department of component police makes a designer's job that much more difficult. Here's why.

These people have the justifiable responsibility of making sure the corporate inventory doesn't get overwhelmed by several variations of the same part, when in reality, only one type is needed. They also want to ensure that the designer's choices will be available for the life of the product, are not over-priced, and have multiple sources. Sometimes, though, they go a bit overboard in their zeal and may not always understand the components or the reasons for a choice.

Take a simple resistor -- one company's NPI (New Product Introduction) group insisted that there were really only a handful of necessary resistor values. Its component engineer (a purely digital type) was looking at those resistors as logic pull-up or pull-down. I had to explain that you can't always make a voltage divider out of 1kΩ and 10kΩ resistors, and yes, there was a good reason for the required 1 percent tolerance. Same for capacitors: Sometimes the company standard Y5P dielectric 0.1µF logic decoupling cap is not suitable for analog circuits.

I remember an incident where a colleague had designed in an octal latch -- I think it was a 74LS373 -- and on going over the timing analysis, I realized that the 20nsec data hold time would be a problem. The component cop continued to allow usage of the LS family because it was so ubiquitous and unlikely to go obsolete, but balked when I told him I wanted to use the ALS family in this particular function because of its much shorter hold time.

He was of the opinion that ALS was a passing fad, so I then told him I was going to use the F373 instead. He wanted to know why I wanted to use the F family, I told him simply "Because you won't let me use ALS." He finally agreed that maybe the LS device was not suitable and agreed to the F version. One of my engineering colleagues actually tried to specify IC sockets on his BOM (bill of materials) to prevent the cops from squelching his design choices, figuring that once the PCB was a done deal, there wasn't much that they could do. Of course, he wasn't successful in this attempt to put one over on them.

At Northern Telecom everybody hated the Components Engineering department. But I saw many times where they would assist and educate a young and green engineer who didn't understand how to specify components.

One of my favourites was when the quartz-crystal engineer had to educate some designers that crystal load capacitances were standardized and they couldn't just pick any value they liked.

Another time a colleague had to have a resistor go through the full qualification process, lasting several months. While that resistor family was widely used in the company that *value* had never been used before. He was told they couldn't expidite the process.

When Nortel started to collapse, Components Engineering were one of the first groups to be cut. High management figured that function could be performed by the contract manufacturers then being brought in. Bad mistake on top of another, and everyone knows the company's end result.

Overall cost of component (initial price, long term price trending, quality, defect rate, short and long term availability, toxicity, ease of use, end of life terms, alternate sources that are form, fit & function compliant, agency approvals, industy standard, etc..).

Does the component lifecycle match your product life? Does the manufacturer discontinue almost as many components as they release?

Online avalability of comprehensive component information, complete part number, data sheet, package dimensions, tape and reel dwg, pricing, inventory, sample ordering, lifecycle, levels of information provided that does not necessitate a call or email to manufactuer that is diverted to voicemail or answered by automated email away message.

My favorite manufacturer is those that meet all of the above and tries to understand the customer products and personalties, provide appropriate product information in a passive, effective manner, does not hound via phone calls, spam, unplanned visits. Does not feel the need to provide cheap pens that require 110 lbs of pressure to expel ink or conversely leak, various sizes of calenders, and other personalized landfill garbage from China.

You take an adversarial approach. What you call "Component Police" is actually just using good design practice while noticing that the product has to ship. "Favored Vendors" are the ones who deliver product to production in time to meet customer requirements. It also helps to be cost effective so we can pay overheads including ourselves.

I once looked at switching a diode package which would help design for manufacture. It turned out the desired component which was an industry standard was 26 weeks lead time when we had 250K of the other in stock. I did not change it and kept my friends in purchasing and logistics still as friends.